1. Field of the Invention
The present invention relates to an automatic toroidal core winding apparatus able to wind toroidal coils by winding wire in a spiral on a toroidal core. The invention particularly relates to an automatic toroidal core winding apparatus that can wind wire on a toroidal core while minimizing the load on the coil and maintaining the wire at a constant tension.
2. Related Art Description
FIGS. 15, 16, 17 and 18 illustrate the principle of winding coil wire on a toroidal core using a supply ring and winding ring. A supply ring 71 and winding ring 72 are provided with pullout or open/close type ring openings 74 and 75 to enable the toroidal core 73 to be arranged with the rings 71 and 72 passing through the center hole of the core 73. In the prior art the openings 74 and 75 are opened manually and the toroidal core 73 is passed through the openings so that each ring passes to the center hole 73a of the core, with the central axis 73b of the toroidal core 73 at right-angles to the central axis 70 of the rings.
The supply ring 71 has a U-shaped groove 71c around its circumference. In order to enable wire 9 to be wound onto the groove 71c, the end of the wire 9 is manually attached to a hook (not shown) on the supply ring 71. The winding ring 72 has substantially the same diameter as the supply ring 71, with which it is aligned concentrically. The supply ring 71 has a wire guide 76 via which wire 9 is drawn from the supply ring 71 and a guide roller 77 to guide the wire 9.
In an actual winding operation, first the toroidal core 73 is manually inserted onto the rings 71 and 72 via the openings 74 and 75 to position the core 73 as shown in FIG. 16. The end of the wire 9 is then attached to the supply ring 71 and the supply ring 71 is rotated around its central axis to wind the required amount of wire into the groove 71c. After cutting the trailing end of the wire 9, the cut end is passed through the wire guide 76 and around the guide roller 77, and is drawn radially outwards from between the rings and affixed to a retainer means or the like (not shown) provided on the periphery of the toroidal core 73. In this state, the wire wound around the supply ring 71 is spirally wound a required number of turns around the toroidal core 73, and the wire left over on the supply ring 71 is manually removed. Finally, the toroidal core wound with the wire, that is, the toroidal coil, is removed.
As shown by FIG. 17, when the toroidal core is being wound, a drive (not shown) is used to rotate the supply ring 71 and winding ring 72 in the opposite direction from that used to load the wire 9 onto the supply ring 71, and the wire 9 is drawn from the supply ring 71 through the wire guide 76 and guide roller 77 on the winding ring 72 and attached to the toroidal core 73. At this time, the wire 9 is subjected to a prescribed tension imparted by the frictional force between the supply ring 71 and the supply ring 71""s support surface (not shown). This tension is for preventing the wire 9 coming off the supply ring 71. As can be seen in FIG. 18, the passage of the guide roller 77 through the center hole 73a of the toroidal core 73 subjects the wire 9 to an extreme degree of bending, imposing a large load on the wire 9. This limits the runout of the wire 9, so that the wire 9 is wound around the toroidal core 73 with no slack.
Thus, much of the winding procedure in the case of this type of prior art toroidal core winding apparatus is performed manually, so the productivity is low, and reliability is also a problem. From the standpoint of quality and cost, this has created a strong demand for automation of the winding procedure.
Moreover, since tension is imparted to the wire 9 by frictional force between the supply ring and the ring support surface, any fluctuations in the inertial force of the winding ring during winding acts directly on the wire 9, in addition to which the wire 9 is subjected to a large load when the guide roller passes through the core hole 73a. This can make it impossible to maintain the wire 9 at a constant tension, leading to a large difference between the winding force on the inner and outer surfaces of the toroidal core. In some cases, there is a risk that this will damage the insulation or break the wire.
Japanese Patent Laid-Open Publication No. Hei 6-342730 describes a method of suppressing insulation damage and the like by increasing the diameter of the guide roller. However, the size of the guide roller is limited by the size of the center hole in the toroidal core 73 through which the roller must pass. Moreover, as shown in FIG. 18, the center of the winding portion of the toroidal core 73 is offset by a distance E from the central axis of the winding ring 72. Because of this, with the rotation of the winding ring 72, the distance between the wire supply position, as defined by the guide roller 77, and the winding portion of the toroidal core 73 is constantly changing. During each rotation used to wind the wire onto the core, this gives rise to a region R1 at which the wire 9 is pulled taut and a region R2 at which the wire 9 is slack. This lowers the alignment degree of windings, making it impossible to achieve a high-density winding.
In view of the above drawbacks of the prior art, an object of the present invention is to provide an automatic winding apparatus that automates the winding of a toroidal core.
An object of the present invention is also to provide a method of winding a toroidal core that enables a toroidal core to be wound with a high degree of alignment, enabling wire to be wound at a high density.
To achieve the above object, the present invention provides a method of winding a toroidal core, comprising the steps of arranging a toroidal core on a wire supply ring and a winding ring that are concentrically arranged, with the supply ring and winding ring passing through a central hole of the toroidal core, taking an end of a wire wound circumferentially around an outer peripheral surface of the supply ring and drawing the end of the wire through a wire guide attached to the winding ring, rotating the supply ring and winding ring around central axes of the rings in a same direction as that in which the supply ring was rotated when being loaded with the wire, at mutually different speeds, rotating the toroidal core about its central axis simultaneously with the rotation of the supply ring and winding ring, and spirally winding the toroidal core with a length of the wire that corresponds to the difference in rotation amounts of the supply ring and winding ring.
The above object is also attained by providing an automatic winding apparatus for automatically winding a toroidal core, comprising a supply ring on a peripheral surface of which wire is circumferentially wound, a winding ring having a wire guide for drawing the wire from the supply ring, a toroidal core rotation means that supports the toroidal core so that the supply ring and winding ring pass through a central hole of the toroidal core and also rotates the toroidal core about its central axis, a ring rotation means that rotates the supply ring and winding ring around the rings"" central axes in a same direction as that in which the supply ring was rotated when being loaded with the wire, at mutually different speeds, the difference in rotation amounts of the supply ring and winding ring becoming length of wire that is wound on the toroidal core.
It is preferable for the supply ring and winding ring to each be formed in the shape of a C by a slit of a prescribed width provided on the periphery of the rings. The slits can be used to align the rings, facilitating mounting and demounting of cores and the removal of wire.
It is also preferable for the supply ring to be disposed concentrically with the winding ring with the supply ring on the radially inner side of the winding ring, since this makes it possible to prevent the wire coming off the supply ring.
To suppress deformation of C-shaped supply and winding rings, it is also preferable to provide the winding ring with an outer support frame that supports the ring in a way that allows the outer peripheral surface of the ring to freely slide circumferentially. For the same purpose, it is preferable to provide the supply ring with an inner support frame that supports the ring in a way that allows the inner peripheral surface of the ring to freely slide circumferentially.
To enable the end of the wire to be easily fixed to the supply ring, is it preferable to provide the periphery of the supply ring with a wire holder to hold the end of the wire when the wire is being wound onto the supply ring. This can be a resilient strip the resiliency of which is utilized to clamp the end of the wire.
The winding ring can include a wire feed-out hole that runs through from the inside to the outside of the ring, a wire feed-out groove that extends from the outside edge of the wire feed-out hole to one of the edges of the winding ring, and the guide roller mentioned above, located adjacent to the wire feed-out groove.
In this case, it is also preferable to be able to measure the tension of the wire being pulled through the wire feed-out hole and along the feed-out groove, by providing the wire feed-out hole with a tension sensor. It is also preferable to provide a control means that uses the output from the tension sensor for controlling the differential rotation drive so that the wire tension remains constant.
The ring rotation mechanism can include a plurality of winding ring drive rollers and a plurality of supply ring drive rollers, the winding ring drive rollers being spaced at equal intervals around the winding ring in contact with the outer peripheral surface of the ring, forming a circle that is concentric with the ring. Similarly, the supply ring drive rollers are spaced at equal intervals around the supply ring in contact with the outer peripheral surface of the ring, forming a circle that is concentric with the ring.
In this case, it is also preferable to be able to measure the load torque acting on the supply ring drive rollers by providing a torque sensor and a control means that uses the output from the torque sensor for controlling the differential rotation drive so that the load torque remains constant.
It is also preferable for the wire guide to be a kink prevention means that utilizes force balancing based on the wire tension. The kink prevention means can comprise a pair of guide rollers and a support plate that rotatably supports the guide rollers and is rotatably attached to an edge surface of the winding ring, with the centers of rotation of the guide rollers and support plate being parallel to the axis of rotation of the winding ring.
To ensure that the toroidal core is properly supported and rotated, it is also preferable for the toroidal core rotation mechanism to include at least two drive units, with each drive unit having at least three rollers and a drive belt on the rollers, the toroidal core being held by a prescribed force between the drive belts of the drive units, in which state the toroidal core is rotated by the drive belts.
Further features of the invention, its nature and various advantages will be more apparent from the accompanying drawings and following detailed description of the invention.